Crank-case-venting means for pneumatic tools



March 11, 1930. A. LEVEDAHL ET AL 1,750,013

CRANK CASE VENTING MEANS FOR PNEUMATIC TOOLS F'iipd Nov. 8, 1925 UNITED STATES.

Patented Mar. 11, 1930 PATENT OFFICE AXEL LEVEDAHL AND REINHOLD Al INORLING, F AURORA, ILLINOIS, ASSIGNORS TO INDEPENDENT PNEUMATIG TOOL COMPANY,OF CHICAGO, ILLINOIS, A CORPORA- TION" OF DELAWARE cnAnK-oAsE-vnn'rme MEANS non PNEUMATIC moons Application filed. November S, 1923. Serial No. 673,471.

This invention relatesto air venting means for crank cases of piston actuated portable pneumatic drills and like tools.

1 In general, our invention has reference to an air venting means operated through centrifugal forces set up on rotating the crank shaft as describedand claimed in our copending applications Serial Nos. 67 3,469 and 67 3, 170, both filed November 8, 1923.

i 201Serial No. 607,498.

j'weight and showing the associated parts of Our presentinvention has particular reference to a form of air ventlng means operating on that principle but applicable to tools of sizes smaller than the ones shown and described in' our said oopending applications, and more specifically to tools'havingldetachnecting Our invention consists further in the matters hereinafter described and more particularly set forth in the appended claims.

In the accompanying drawings- Fig. 1is aside view of a tool of the character described havlng incorporated therein 1 j j or more passages 20 arranged at an angle to throu 'h said means and associated parts-of the to al; and

Fig. 3 is a bottom plan view of the counteri the air venting structure.

As shown in Fig.1, the tool to which our invention particularly relates has an outside case or housing 1 provided on one side with a combined handle and throttle 2 through j which compressed air or other motive fluid is j admitted to the tool for operating the same.

I j j handle, 3 of the loop or closed grip type. On

the other side of the case is the-spindle 4:

At the upperendof the case, the toolhas a carrying a twist drill 5, as shown. This type of tool is provided with a pair of cylinders 6, 6oneach side, only one pair being shown f "position, when the drill is idle, the ball valve 1 j inthe drawings. The cylinders are given a V the crank shaft 9.

arrangement and in them work single-acting pistons 7 connected by connecting rods 8 with the crank shaft 9 is j ournaled in an antifriction ball bearing 11 in is removably connected with the crank shaft at the end journal in accordance with the disclosure made in said Hanssen application, Serial No. 607 A98. Removability of the counterweight 14: is made necessary by reason of the one-piece bearing sleeves or members 15, 15 carried by theoonnecting rods 8.

The bore 13 opens at its outer end into an air receiving chamber 16 formed above the same in the closure 12. This chamber 16 finds outlet to the atmosphere through a series of outlet ports 17 drilled or otherwise formed in the same. Extending intothebore 13 from the chamber 16 is a stationary tube 18 carried at itsupper end by a cup 19 having a central portion forming the bottom wall of the chamber 16 and its side portions annular and engaging against the end block 12.

The counterweight 14: is provided with one the bore 13 and opening at their inner ends into, the same through connecting ports 21 formed in the end journal 10. These pasfsages open at their outer ends into enlarged chambers 22 formed in the counterweight 14, as shown Each. chamber 22 has a restricted inner portion 23 forming a seat for a ball valve 24-, which when open rests against a stop pin 25carried by the counterweight 1 1 in the associated end chamber 22,

asshown in Fig. 2. 1 j j In use, the drill maybe held in various.

[working positions, depending on the lay of the work. When the drill is held in the position shown in Figs. 1 and 2, the end journal 10: is uppermost and the drill bit 5 and the passage 20 bothextend downward with the stop pin 25below the ballvalve 24,- In this 24 will automatically unseat and come to rest against the stop pin 25 by the force of gravity.

' set valve 24 will, when the drill is idle, automatically seat itself and close the vent by the force of gravity. \Vhen the tool, however, is operated in this inverted position, centrifugal forces which are set up by rotation of the crank shaft 9 will automatically .unseat the valve and retain the latter in its unseated position against the stop 25 during the operation of the drill for ventingof the crank case through the passages as before. Should the tool be stopped in this inverted position, the ball valve will close by gravity and prevent any lubricant leaking out .of the .case through the vent .assages.

When he drill is held in a position with the drill bit .5 and crank shaft 9 horizontal, the ,end journal 10 will be likewise disposed, and the valve 24 will automatically seat by gravity should the crank shaft be stopped with the passage 20above the axis of the shaft. Startmg the drill with the crankshaft in this position, the valve 24 will be automatically unseated to {open the vent by centrifugal forces on. the rotation of the crank shaft. Shou d the crank shaft be stopped while the tool is held in thishorizontal position with,

the assage 20 below the axis .of the shaft, the". all valve will automatically unseat by gravity, and in starting the drill from this position, centrifugal forces set up on the rotation of the crank shaft will co-operate with gravity to hold the valve 24 open to vent the crank case.

Should the drill be held in any position at an angle, either up or down, to the several specified positions mentioned, the valve 24 will become automatically unseated either by grant-y or centrifugal forces, depending on whether the passa e 20 downward, as will be apparent; centrifugal forces, however, playing an important part in either automatically unseating the valve or co-operatmg with gravity to retain the valve unseated during-the operation of the tool should the crank shaft be started from a posi tion with the valve initially opened by The lubricant in the crank case is applied to the moving parts by a splash method.

Thi has slow' moving properties and, being a ier than a r, ing opening 20 during therotation of the crank sha $0 thatnone o i is' rrie out with the escaping air. The structure deopens upward or is thrown from the vent-.

scribed prevents an accumulation of air pressure in the case 1 from leaking of the compressed air into the case past the pistons and valves, without an opportunity afforded for the lubricant in the case finding its way out of the case with the escaping air. With the passages 20 inclined to the axis of the crank shaft, any lubricant finding its way into the same will be thrown back into the case by centrifugal force and not allowed to be carried out through the escaping air.

Fig. 3 shows that a plurality of passages 20 are provided in the counterweight 14, and thus a plurality of ball valves 24 therefor are used. This is done for the reason that the space within the tool is small and a large chamber or passage for the venting of accumulated air is out of the question. Suflicient area for this outlet passage is gained by a plurality of them, as described. The

handle 3 is secured to the closure 12. The counterweight 14 has a tapered bore 14 to fit a tapered part 9 of the crank shaft 9 just inside of the closure block 12 and is keyed thereon, the keyway' 14 being shown in Fig. 3. A tension plate 26 is clamped between the parts on the crank case 1 and end block 12 and holds theoutside bearing ring 11 in place, as in said Hanssen application.

While we have shown and described herein in detail an air venting means constructed in accordance with our invention, it is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and scope of our inventio We claim as our invention:

1. In a piston actuated pneumatic tool, the combination with a crank case, of a handle carrying block at one end of the case and having one or more air outlet ports, a crank shaft in said case and having an end journal supported by said block, a counter-weight in the case at said block and mounted on said shaft, said shaft and counter-weight having air outlet passages communicating with the exterior of the case and ports, respectively, and a valve carried by the counterweight in the passage thereof for controlling the saine, said valve being opened by centrifugal forces set up on rotating the crank shaft.

2. In a piston actuated pneumatic tool, the combination with a crank case, of a handle carrying block at one end of said case and having an interior vent chamber with outlet ports, a crank-shaft in the case and having an end journal supported by said block, a counter-weight in the case at the block and mounted on the crank shaft, said end journal and counter-weight having air outlet passages communicating with the interior of the case and said chamber, respectively, a cup-shaped member fittin in said chamber .over the end journal, a tube carried by said 

